Obesity is a state in which fat is excessively accumulated in a body (Non-Patent Literature 1), hyperlipidemia, hypertriglyceridemia (TG), and causes lifestyle diseases such as lipid metabolism disorder, fatty liver, diabetes, hypertension, arteriosclerosis, etc.; cerebrovascular disease, coronary heart disease, dyspnoea, lumbago, knee osteoarthritis, etc., and among obesity, those involving these diseases, or having a possibility of causing these diseases in the future are defined to be obesity and handled as one disease.
DGAT is an enzyme catalyzing a reaction from diacylglycerol to TG which is the final stage of TG synthesis, and it has been known that two kinds of subtypes of DGAT1 and DGAT2 exist in DGAT. Of these, DGAT1 has been known to exist in liver, skeletal muscle, adipocytes, etc., and to participate in TG synthesis in the respective tissues (Non-Patent Literature 2).
Also, at the time of TG absorption at the small intestine, TG is decomposed to fatty acid and monoacyl glycerol by pancreatic lipase in lumen of the small intestine, then, took into small intestinal epithelial cells, and absorbed after resynthesis to TG in the epithelial cells. It has also been known that DGAT1 is participated in TG resynthesis at the final stage in the small intestinal epithelial cells (Non-Patent Literature 3).
Thus, a drug which inhibits an action of DGAT1 can inhibit the final stage of TG synthesis so that it can not only inhibit TG synthesis in adipocyte, liver, etc., but also inhibit TG resynthesis in the small intestine, whereby it is expected to inhibit TG absorption in the small intestine and the diseased state of obesity can be improved (Non-Patent Literature 4).
Further, a thesis that accumulation of TG in liver, skeletal muscle, etc. (ectopic adiposity) is a cause of insulin resistance of type 2 diabetes accompanied by obesity has widely been accepted, so that it has been said that a drug which inhibits an action of DGAT1 is expected to improve insulin sensitivity and to have a treatment effect on type 2 diabetes by reducing ectopic adiposity (Non-Patent Literature 4). Also, it has been reported that improvement in insulin sensitivity can be admitted in a mouse in which DGAT1 is knocked out by gene manipulation (DGAT1 knockout mouse) as compared with that of a wild type mouse (Non-Patent Literature 5). Recently, it has also been reported that the compound which inhibits the action of DGAT1 stimulates actions of glucagon-like peptide-1 (GLP-1) and a protein which causes loss of appetite (anorexia) (Non-Patent Literature 6).
As a compound having a continuous arycyclic structure, the following have been known. For example, Patent Literature 1 discloses (2S)-2-[4′-(1-benzyl-1H-benzimidazol-2-yl)-biphenyl-4-yloxy]-3-phenyl-propionic acid (Example 70), etc., as a compound which inhibits Protein-tyrosine phosphatases (PTPases), and useful for the treatment of obesity, glucose intolerance, diabetes, hypertension, and insulin tolerance accompanied by ischemic disease.
Patent Literature 2 discloses, as a compound having Protein-tyrosine phosphatase-1B (PTP-1B) inhibitory activity useful for the treatment of type 2 diabetes, 2-benzyl-4-[4′-(2-benzyl-benzofuran-3-yl)-biphenyl-4-yl]-4-oxo-butyric acid (Example 1), ({4′-(3-benzylamino)imidazo[1,2-a]pyridin-2-yl)biphenyl-4-yl}oxy)(phenyl)acetic acid, {[4′-(5-methyl-1H-indol-1-yl)biphenyl-4-yl]oxy}(phenyl)acetic acid (Example 3), etc.
Patent Literature 3, Patent Literature 4 and Patent Literature 5 disclose compounds having structures in which biphenyl having an inhibitory activity against factor VIIa, factor IXa, factor Xa and factor XIa, and a nitrogen-containing fused hetero ring are bonded. However, their chemical structures are limited to the structures in which the nitrogen-containing fused hetero ring is bonded to 3-position of the biphenyl.
Patent Literature 6 discloses 2-[[2′-(5-phenyl-1H-imidazol-2-yl)[1,1′-biphenyl]-3-yl]oxy]acetic acid (Example 46), etc. as a compound having a treatment effect on obesity and diabetes by inhibiting adipocyte-type fatty acid binding protein (aP2).
Non-Patent Literature 7 reports 2-[[2′-(1-ethyl-4,5-diphenyl-1H-imidazol-2-yl)[1,1′-biphenyl]-3-yl]oxy]acetic acid, 2-[[2′-(4,5-diphenyl-1H-imidazol-2-yl)[1,1′-biphenyl]-3-yl]oxy]acetic acid, etc. as a compound binding to adipocyte-type fatty acid binding protein (aFABP).